I thought, I had better put up a second post about that human powered flying machine thing I was thinking about.

It turns out that these things have been in steady development over the last few decades. NASA have had a couple of goes at it - they still hold the record for distance 115km done in a little under 4hrs.  Although I don’t know who to believe, NASA say 199km, FAI (who keep the records) say 115km.  Since then, the main development seems to be by Japanese students trying out for the Birdman Rally which they run there every year. The record for distance in that competition is 34km.  I guess it comes down to a matter of fitness.

So it seems I need not wonder if it’s possible, or if humans can generate enough power, apparently they can! Just on that, it seems that 200W is the figure to go on for flights of any duration. Elite athletes can conjure up more for short periods, 1600W and 1000W for a few minutes, or 2000W for instantaneous measurements.

So I want to know why we aren’t all using them to get around in? Well there’s the The Royal Aeronautical Society Human Powered Flight Group who are wondering the same thing. They have put up a prize for first sports flyer that can be used for racing and the like and a second prize for first flyer to cover the distance of a typical marathon in under 1 hour.

We I looked into it a bit more, it’s easy to see why these things aren’t common place. They can only fly in all but the stillest of air, they typically have 20m - 35m wing spans and do not handle anything more than slight turns. Not exactly convenient.

This hasn’t ended my thoughts on this though, all it’s done is make me wonder how these things can be made better. After all, someone has already flown one 115km. Now I assume that they didn’t take it all that high as they probably didn’t want to risk their life, so they’ve got to pedal constantly, which was a huge effort probably. But in reality, once the risks were reduced (ie. take a parachute), wouldn’t you get up a bit of height, pedal pedal pedal - then glide? Find a thermal maybe - pedal some more, gain even more height - then glide maybe even the rest of the way?

I left this discussion last time on whether wings or propellers are better? All the ones made so far have large propellers, driven by pedals and chains as far as I can tell. Maybe a dynamo and motor might be another option in certain circumstances as well. But what about flapping wings? Ornithopter is what you call something with flapping wings. Planes have been designed as such, but gee they look ugly! Plus, they make an unpleasant racquet. Of the radio control variety, there do seem to be a couple of exceptions. One, which has stiff foam wings looks a bit like a flapping glider, it appeared to fly effortlessly!

The only reason why I want to consider the alternative is that propellers were developed along with an engine with a rotating shaft. They went very well together at the time. The Wright Bros actually had a little 4 cylinder engine built for them which was lighter than normal. Engines were developed further and hence the propellers have their place ever since. Now considering things for human power I didn’t want to assume the propeller would be best just because they are so widely used.

But I don’t know. Maybe propellers are best, and flapping wings around is just a bit impractical. Obviously, one of the main factors is efficiency. Are they more efficient, both when in use and when not? That is, when you’re not driving flapping wings or a propeller, is the aircraft a good efficient glider? When in use, do they use the available energy efficiently?

I’ll look into that more between now and next time

This entry was posted on Tuesday, July 18th, 2006 at 2:08 pm and is filed under My thoughts. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.